Machine for coating sheets of paper and the like with liquid coating materials

ABSTRACT

A machine for coating sheets of paper and the like with liquid coating materials, in which the sheets are conducted without the application of pressure between a smooth coating roller and a larger diameter format roller, preferably rotating at different peripheral speeds, for coating the entire surfaces of said sheets, a feed roller accepting the coating material from a fountain roller dipping into a supply of coating material and transferring a film of desired thickness to the coating roller. For applying the coating material to predetermined parts of the surfaces of sheets the smooth coating roller together with special chocks mounted in bearing supports is removable from the machine and replaceable by a screen roller provided with screen surfaces corresponding to the surfaces that are to be coated. The screen roller revolves at the same peripheral speed and has the same diameter as the format roller, besides being mounted in taller chocks adapted to its larger diameter, but insertable into the same bearing supports. A doctor blade cooperates with the screen roller attachable to existing fixing means. The format roller is designed to withstand the high roller pressures required for gravure printing.

I United States Patent 1 Kumpf Oct. 30, 1973 MACHINE FOR COATING SHEETSOF PAPER AND THE LIKE WITH LIQUID COATING MATERIALS [76] Inventor:Wilhelm Kumpf, No. 38, Am Anger,

Erlangen, Germany [22] Filed: Sept. 1, 1971 [21] Appl. No.: 176,856

[30] Foreign Application Priority Data Primary Examiner-Henry S. JaudonAttorney-Jacobs & Jacobs [5 7] ABSTRACT A machine for coating sheets ofpaper and the like with liquid coating materials, in which the sheetsare conducted without the application of pressure between a smoothcoating roller and a larger diameter format roller, preferably rotatingat different peripheral speeds, for coating the entire surfaces of saidsheets, a feed roller accepting the coating material from a fountainroller dipping into a supply of coating material and transferring a filmof desired thickness to the coating roller. For applying the coatingmaterial to predetermined parts of the surfaces of sheets the smoothcoating roller together with special chocks mounted in bearing supportsis removable from the machine and replaceable by a screen rollerprovided with screen surfaces corresponding to the surfaces that are tobe coated. The screen roller revolves at the same peripheral speed andhas the same diameter as the format roller, besides being mounted intaller chocks adapted to its larger diameter, but insertable into thesame bearing supports. A doctor blade cooperates with the screen rollerattachable to existing fixing means. The format roller is designed towithstand the high roller pressures required for gravure printing.

6 Claims, 3 Drawing Figures MACHINE FOR COATING SHEETS OF PAPER AND THELIKE WITH LIQUID COATING MATERIALS BACKGROUND OF THE INVENTION Thisinvention relates to a machine for coating sheets of paper and the likewith liquid coating materials, particularly with gloss or coloredvarnishes or adhesives. Coating the entire faces of sheets of paperusually presents no major difficulty. The coating material can beapplied-in the same way as the ink in rotary printing presses by asystem of rubber rollers. Substantially this system comprises a fountainroller which dips into a supply of the coating material and delivers thesame through an intermediate transfer or feed roller in the form of afilm of the desired thickness to a third roller which functions as acoating roller. The latter applies the material to the sheets which areconveyed through the gap between the coating roller and a cooperatingcounter-roller.

The counter-roller is analogous to a cylinder known in gravure machinesas the format cylinder. It will therefore hereinafter be described asthe format roller, because it likewise carries a rubber blanketunderneath which a flat insert is placed of the same format as the sheetthat is to be coated. The resultant raised backing for the sheet ensuresthat only the face of the sheet will be coated but that the remainder ofthe format roller will remain free of coating material.

However, contrary to gravure machines no pressure is exerted between thecoating roller and the counterroller, since otherwise the film ofvarnish or the like would be squeezed out. The two rollers are adjustedto leave a gap sufficiently wide to permit the coating material to beapplied to the sheet by light contact. A gentle rubbing motion of thecoating material is in fact advantageous. Consequently the coatingroller and the counter-roller are driven at slightly differentperipheral speeds. Analogously, no contact pressure is created betweenthe fountain roller, the feed roller and the coating roller. They arelikewise placed close enough for the transferred lacquer or like film tohave the desired thickness. Since none of the four rollers is requiredto withstand major stability stresses each may be a lightweight metalcylinder, the coating, feeding and fountain rollers being provided withpolished rubber coverings. Moreover, in order to achieve a more uniformdistribution of the coating material that is applied to the sheets thecircumference of the rubber coating roller is also shorter than thelength of the sheet or the circumference of the format roller.

Lacquering and like coating machines of the described kind for coatingone complete side of sheets are known in the art. They worksatisfactorily and can be produced at low cost so that their employmentis economically justified although they are merely auxiliary surfacefinishing machines that have a low product value compared to that ofprinting machines.

However, frequently the need arises not only of coating one completeside of paper or like sheets with liquid materials, but also of coatingonly particular parts of the sheet surface, for instance in theapplication of coloring or gloss varnishes to paper that is to be usedfor packing, when certain surfaces are to be kept free of varnish toenable them to accept glue. Moreover, in order to economise in theconsumption of say varnish, it is advantageous to coat only thoseportions of the surface that can later be seen, for instance in foldingpackages in which large parts of the paper surface are hidden.

In the printing art the inking of part of the surface of sheets isalready done in color printing. For this purpose gravure machines areused in which the printing cylinder has a screen corresponding to thesurfaces that are to be inked. An excess of ink is applied to thesescreens and the surplus is removed with a doctor. The ink which remainsin the cells of the screen is then transferred to the sheet by theapplication of considerable pressure. Gravure machines of this kind arelarge and expensive rotary machines for the production of glossymagazines, books and the like. Their employment for partly coatingsheets merely for the purpose of imparting to their usually previouslyprinted surface a greater advertising appeal by the application of agloss varnish or of providing certain portions with an adhesive would beentirely uneconomical. Machines for performing these latter tasks maycost only a small fraction of the investment cost of a gravure machineif they are to be economically acceptable.

It has also been proposed to solve the problem of coating part surfacesby using plate cylinders in which the surfaces that are to be coated inthe same way as the plates in relief printing are in relief. However,difficulties arise in the distribution of the coating material,particularly at the edges of such plates.

SUMMARY OF THE INVENTION The invention seeks to improve the firsthereinabove described machine that comprises a rubber roller system forcoating the entire side of sheets, the object of the invention being tomodify such a machine without major expense so that it can be convertedinto a machine for coating only predetermined portions of the surfacesof sheets. This makes the provision of a second independent machine forsuch a purpose unnecessary.

For achieving this object the present invention consists in that forapplying a coating material to predetermined parts of the surfaces ofsheets the smooth coating roller together with a pair of special chocksmounted in bearing supports is removable from the machine and replacableby a screen roller provided with screen surfaces corresponding to thesurfaces that are to be coated, the screen roller revolving at the sameperipheral speed and having the same diameter as the format roller,besides being mounted in a pair of taller chocks that are adapted to itslarger diameter but are nevertheless insertable into the same bearingsupports, a doctor blade cooperating with the screen roller beingattachable to existing fixing means and the format roller designed towithstand the high contact pressures required in gravure printing.

Since the circumference of the smooth rubbercovered coating roller forcoating the entire face of the sheets must be shorter than the length ofthe sheets, and also than the circumference of a screen roller, in orderto ensure a uniform distribution of the coating material on the face ofthe sheet, the feed roller must be withdrawn when the machine isre-equipped. For this reason a useful feature of the invention consistsin that the feed means for the coating material which in theconventional manner substantially comprise a fountain roller dippinginto a supply of coating material, a feed roller accepting the coatingmaterial from the fountain roller and transferring the same as a film ofthe desired thickness to the coating roller, as well as adjusting means,are mounted as a unit assembly on a common frame portion which can beadvanced and retracted a distance that makes allowance for the differentdiameters of the coating rollers that can be fitted into the machine.

BRIEF DESCRIPTION OF THE DRAWINGS These and other useful features of theinvention will be understood as the following description of embodimentsof the invention proceeds, in which reference will be made to theaccompanying drawings which are illustrative schematic side elevationsof essential parts of the proposed machine.

FIG. 1 is a machine for coating the entire surface of sheets by means ofa rubber roller,

FIG. 2 is a machine for coating required parts of the surface of sheets,and

FIG. 3 is the coating machine according to FIG. 2 showing the sheet feedmeans in raised position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the coatingmachine illustrated in FIG. 1 a roller 1 has a polished rubber covering.The purpose of this roller 1 is to apply a coating material to sheetsthat are conveyed from right to left in FIG. 1 through the gap betweenthe coating roller and a cooperating counter-roller 2. The coatingroller 1 obtains the coating material from a feed assembly marked 3substantially comprising a fountain roller 4, a feed roller 5 and afountain 6 for the coating material. The fountain roller 4 dips into thefountain and transfers parts of the material which it picks up to thefeed roller 5 which transfers a desired thickness of film to the coatingroller 1. Adjusting means 7 and 8 are provided to adjust the rollerclearances and the required thicknesses of the film of material that istransferred from the fountain roller 4 to the feed roller 5 and fromsaid feed roller to the coating roller 1.

The counter-roller 2 is a format roller. A rubber blanket 9 is wrappedaround its circumference and clamped in position. Underneath the rubberblanket 9 is an insert which in size corresponds to the format of thesheet that is to be coated. This insert creates a slightly elevatedbacking for the sheet. Consequently the coating material will be appliedby the coating roller 1 only to the sheet and not to other parts of theformat roller 2.

The individual sheets are positioned in relation to the insert byconventional gripper feed means travelling in an endless path at theperipheral speed of the format roller 2. The gripper feed means comprisetwo chains 10 adjacent the side faces of, and driven by the formatroller 2. They are mounted on cross members spaced between the chains 10at equidistant intervals but not shown in the drawings. These grippersconsecutively grip the sheets at the machine entry side, draw themthrough the gap between the two rollers 1 and 2 whilst being receivedinto a longitudinal recess 11 in the format roller 2, and convey thesheets into proximity with a pair of return wheels 13 mounted somedistance away on a cantilever frame 12, where the sheets are released.

There is no contact pressure between the coating roller 1 and the formatroller 2, these two rollers being adjusted to the appropriate clearancefor the coating to assume the required thickness. For this purpose theformat roller 2 has a fine adjustment for elevation, as illustrativelyindicated in FIGS. 2 and 3 by an eccentric bearing 15 for the formatroller shaft 16, and a worm 14 for rotating the eccentric bearing.

The diameter of the coating roller 1 is significantly less than that ofthe format roller 2. It has been found that the uniformity of thecoating applied by the coating roller 1 is disturbed at higher speedsbefore it makes contact with the sheet if the diameter of the rollerexceeds a given size. Coating roller 1 and format roller 2 also haveslightly differing peripheral speeds to generate a gentle rubbing actionof the coating material.

For changing the machine over from the described process of coating theentire surface of the sheets, as shown in FIG. 1, to coating only one ormore parts of the surface of the sheets, the smooth coating roller 1 isremoved and replaced by a screen roller of the same diameter, and drivenat the same speed as the format roller 2. In order to facilitatedismantling and assembling the rollers the coating roller 1 is mountedin special chocks 17 which are received into ways 18 in bearing supports19 which they are bolted to.

Referring to FIG. 2 in which the same reference numerals as in FIG. 1identify like parts, the screen roller 20 which has replaced the smoothcoating roller 1 (FIG. 1) is likewise mounted in suitable chocks 21.Owing to the larger diameter of the screen roller 20 these chocks 17 arehigher than those shown in FIG. 1, but they fit into the same ways 18 ofthe bearing supports 19. The same holes can also be used for bolting thechocks in position.

The position of the feed roller 5 must be adjusted to the largerdiameter of the screen roller 20. In order to simplify this operation itis useful to combine the entire feed assembly 3, substantiallycomprising the fountain roller 4, the feed roller 5 including theadjusting means 7 and 8, and the fountain 6 itself, in a single unitassembly. This may be mounted in a special portion 22 of the frameattached by screws 23 to its base. After undoing these screws 23 theentire multi-component feed assembly 3 can be moved back a suitabledistance determined by tapped holes 24 for the reception of the screws23.

The screen roller 20 is provided, directly on its surface or on a metalplate thereon, with a screen similar to that used in photogravure, thescreen covering those parts which correspond to the parts on the sheetsthat are to be coated. In order to remove from the regions outside thecells of the screen the unwanted coating material which has been appliedto the entire surface of the screen roller 20, a doctor 25 is used whichis mounted, together with its holder, on fixing means 26. In thesimplest case the latter may merely be tapped holes for the reception offixing screws.

Whereas in a machine equipped with a rubber coating roller for coatingthe entire surface of the sheets the format roller is not submitted tocontact pressure and may therefore be of light-weight construction, itis called upon, in the embodiment of the machihe according to FIGS. 2and 3, to press the sheet against the screen roller with a considerableamount of pressure, as in gravure printing. The format roller 2 istherefore designed for withstanding such high pressures and remains inthe machine even when the entire face of the sheet is to be coated and arubber coating roller 1 (FIG. 1) is used.

Consequently, if it is desired to re-equip a machine using a rubbercoating roller for coating the entire sheet surface for the purpose ofcoating only parts of the sheet surface, it is in practice onlynecessary, apart from one or two minor changes to be made in the machineitself, to provide an additional screen roller and a doctor, i.e., anexpense which is in no way comparable to the cost of a second machine.

The change-over itself is likewise not very difficult and can beaccomplished within a short time. The work can be significantlyfacilitated if the cantilever frame 12 carrying the pair of returnwheels 13 can be hingeably raised. For this purpose the cantilever frame12 which substantially consists of two sides that are connected togetherat suitable points may be hinged coaxially with the format roller shaft16, either on this shaft itself or in a machine frame 27 in alignmenttherewith, the cantilever frame resting on supports provided on themachine frame 27 when in the working position shown in FIGS. 1 and 2.Lifting means, such as hydraulic ram cylinders 28 attached to eachcantilever half, may conveniently be provided for raising the frame 12.To avoid the coating roller 20 or 1 (FIG. 1) being in the way, thisroller may be retractable. For this purpose the bearing supports 19 mayhave extensions which carry the frame portion 22 supporting the coatingroller assembly, the extensions forming a slide 30 movable in specialways in the machine frame 27. Two coupling rods 29 may be linked at oneend to side members of the cantilever frame 12 and at the other end tothe slide 30 in such a manner that when the cantilever frame 12 israised the slide 30 will be automatically moved out of the way togetherwith the assembly which it supports. When the cantilever frame 12 israised the delivery side of the machine is fully accessible for theinsertion and adjustment of the inserts on the format roller 2, forcleaning the rollers, exchanging the coating rollers 1 or 20 forinspecting, repairing and so forth.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The embodimentsare therefore to be considered in all respects as illustrative and notrestrictive.

What is claimed is:

1. A coating machine comprising (a) a frame, (b) a format rollerrotatably mounted on the frame, (c) a pair of supportsmounted on theframe parallel to the axis of the format rollers and operable to receivechock elements, (d) a first roller and chock assembly comprising (i) apair of chocks mountable in the supports and (ii) a coating rollerrotatably mounted in its associated chocks and being of a diametersmaller than that of the format roller, the chocks of said firstassembly being of a height sufficient to dispose said coating roller andsaid format roller in parallel coating aligment without contactpressure, and (e) a second roller and chock assembly interchangeablewith the first roller and chock assembly and comprising (i) a pair ofchocks mountable in the support and (ii) a screening roller rotatablymounted in its associated chocks and being of the same diameter as saidformat roller, the chocks of said second assembly being of a heightsufficient to provide contact pressure between said format roller andsaid screen roller.

2. A coating machine as defined in claim 1 including (a) coatingmaterial feeding means detachably mounted on said frame, said meanscomprising (i) a fountain roller operable to dip into a coating materialreservoir, (ii) a second feed roller accepting coating material fromsaid fountain roller and transferring the same to a third roller, saidthird roller being either said coating roller or said screen roller,(iii) means for adjusting the distance between the fountain roller andfeeder roller and (iv) means for adjusting the distance between thefeeder roller and said third roller, and (b) means for moving saidcoating material feeding means from a first position on the frame whensaid first roller and chock assembly is disposed in said supports to asecond position when said second roller and chock assembly is disposedin said supports.

3. A coating machine as defined in claim 2 wherein said feeding meansincludes a doctor disposed to engage the screening roller when saidsecond roller and chock assembly is disposed in said supports but notthe coating roller when said first roller and chock assembly is disposedin said supports.

4. A coating machine as defined in claim 1, including stock feedingmeans, said feeding means comprising two endless chains with grippersmounted thereinbetween, said chains running at one end over chain wheelsdisposed coaxially with the format roller and at the other end overchain wheels disposed away from the delivery side of the rollers, saidchain wheels being mounted on a cantilever frame which is hingeablyraisable coaxially with the axis of the format roller.

5. A coating machine as defined in claim 4, wherein the supports andfeeding means are slideably mounted on the frame.

6. A coating machine as defined in claim 5, wherein the cantilever frameis coupled to the feeding means and supports so that raising thecantilever frame about its hinge displaces the support and feeding meansfrom their working position and lowering the cantilever frame returnsthe support and feeding means to their working position.

1. A coating machine comprising (a) a frame, (b) a format rollerrotatably mounted on the frame, (c) a pair of supports mounted on theframe parallel to the axis of the format rollers and operable to receivechock elements, (d) a first roller and chock assembly comprising (i) apair of chocks mountable in the supports and (ii) a coating rollerrotatably mounted in its associated chocks and being of a diametersmaller than that of the format roller, the chocks of said firstassembly being of a height sufficient to dispose said coating roller andsaid format roller in parallel coating alignment without contactpressure, and (e) a second roller and chock assembly interchangeablewith the first roller and chock assembly and comprising (i) a pair ofchocks mountable in the support and (ii) a screening roller rotatablymounted in its associated chocks and being of the same diameter as saidformat roller, the chocks of said second assembly being of a heightsufficient to provide contact pressure between said format roller andsaid screen roller.
 2. A coating machine as defined in claim 1 including(a) coating material feeding means detachably mounted on said frame,said means comprising (i) a fountain roller operable to dip into acoating material reservoir, (ii) a second feed roller accepting coatingmaterial from said fountain roller and transferring the same to a thirdroller, said third roller being either said coating roller or saidscreen roller, (iii) means for adjusting the distance between thefountain roller and feeder roller and (iv) means for adjusting thedistance between the feeder roller and said third roller, and (b) meansfor moving said coating material feeding means from a first position onthe frame when said first roller and chock assembly is disposed in saidsupports to a second position when said second roller and chock assemblyis disposed in said supports.
 3. A coating machine as defined in claim 2wherein said feeding means includes a doctor disposed to engage thescreening roller when said second roller and chock assembly is disposedin said supports but not the coating roller when said first roller andchock assembly is disposed in said supports.
 4. A coating machine asdefined in claim 1, including stock feeding means, said feeding meanscomprising two endless chains with grippers mounted tHereinbetween, saidchains running at one end over chain wheels disposed coaxially with theformat roller and at the other end over chain wheels disposed away fromthe delivery side of the rollers, said chain wheels being mounted on acantilever frame which is hingeably raisable coaxially with the axis ofthe format roller.
 5. A coating machine as defined in claim 4, whereinthe supports and feeding means are slideably mounted on the frame.
 6. Acoating machine as defined in claim 5, wherein the cantilever frame iscoupled to the feeding means and supports so that raising the cantileverframe about its hinge displaces the support and feeding means from theirworking position and lowering the cantilever frame returns the supportand feeding means to their working position.